ONE SMALL STEP . . .

Bill, none of us are expwrts on NEO and earth to space transfer, so why get all defensive?
Look, all Ivve done is reported what I can red about the feasibility of a series of designs in a "Space elevator" (including the challenges),
So far NOONE that spent time associated with the 9 nation study about space elevators had anything of a "fatal flaw" with the technology. The designs of several ways of doing it were being considered as are the "political realities"

The same thing resides with Nuclar rockets. I jut don't think that nuke rockets will leave from earth in the near future, no matter what design tests have shown. The reality is that theres a bigger risk associated with nukes (mostly from perception) and, whether you like it or not, our perception is our reality. The scientific community represents a teeny inner wall of public opinion. SCientists are usually the last guys listened to.
While we can see that nuke rockets "work", that point is entirely irrelevant to such an endeavor.
The game is one of RISK ASSESSMENT and space rockets do NOT have a 100% safety record. There are too many xplosions, fires, incoming nuke reactors from dyung satellites etc. I don't think we will "trust" that technology. SO we are looking for another way to reduce the costs of transferring payload mass into orbit or to the Lgrange points for deep space exploration.

Reinforced carbon fibre matrices with a widening design to the center of the "elevator" has a reality that , for a long run, can show that costs can be kept lower than by the old fashioned way of throwing hardware into space by tossing up even more expendible hardware.

If that sentence is anything to go by Setanta's knowledge of celestial mechanics must be terrible.

That reminds me. Have you heard about the German pessimist vegetarian?

He fears the wurst.

Invincible ignorance--you write of "No where near any of earth Lagrangians points either, by at least a few hundreds thousands miles, with the sun or the moon." News flash, bright boy, at perigee, the moon is about 225,000 miles away and at apogee just over 250,000 miles away. You better go back to your drawing board. The point of the the relationship to Lagrange points is about the stress on the cable. I suggest you read up on carbon nanotube fibers and learn something for change.

I guess it no used trying to explain things to you.

Sad...................

Given that you apparently don't understand it yourself, that seems to be the balance of wisdom on your part.

Our computers , gps, and micro steering systems (in 3 coordinate polar systems) are so mature today that we could pose a "materiel launcher" which is a space "GUN" or an EM "RAILGUN" which would shoot our crap into a medium sustainble orbit where wed have giant steerable "catchers mitts " of C fibre that could do real time steering calculations to generate a DELTA "v" ( which is a very VERY slight difference between the launch package and the catchers mitts) so that they could be caught and then , using small ionic engines attached , could be steered out to the "Lagrangian port"
The earth would certainly provide enough M to enable any size packge of stuff to be launched "rocketless" into orbit.
That's not out of our techy range even now.

Bill makes one good point about establishing a "space based economy" in which such huge investments such as an elevator, large rockets, Lofson loops or railguns could be sustained.
The biggest costs would still be transiting materiel to out there for deep space exploration. Remember the Von Braun SPace Wheel stations. When I was a little kid I used to do drawings of these things . These giant "ports" will be the big investments for staging for going out and returning. They will be a sustaining cost item even as (pwrhaps) individual nations try their own programs for exploration and discovery (and mining elements from At nos 57 -92)

Carbon nano-tube fiber is the materials "wave of the future." I wrote earlier of a carbon/ceramic material. Really, an even better mix would be a matrix of carbon nano-tube and molecular diamond. Molecular diamond lattices are not beyond our technology, but right now are beyond our pocketbooks. The great thing about carbon nano-tube materials is that you could land on any Apollo object or asteroid which is a carbonaceous chondrite, and use robot mining units to extract the carbon. After that, there's almost no limit to what you could build with carbon nano-tube fiber--including the cable for a space elevator. One area we can work on right now, and need to work on AI. With robots possessing sufficiently sophisticated AI, we can send them out into the void, put them to work and forget about them until they call home to say: "We're cone now."

Arthur C. Clarke said the Moon would be ideal as a future base for launching rockets into space via a "rail gun" because there's no atmospheric drag

Also the G field of the moon is tiny compare to the earth so the escape Velocity of the moon is 5,400 mph instead of the earth escape velocity of 25,000 mph.

Or put it another way it take 25 times less energy per mass to leave the moon then the earth.

On the moon rail gun to space surely no problem however from the earth you got to be kidding me.....as you would need many times the del V of 25,000 as the "slug" from a rail gun would need to fight it way out of the earth atmosphere.

So you start with needing 25 times the amount of energy for an earth rail gun launch then the moon and adding the atmosphere you are looking at maybe 50 times the energy.

Oh I forget nothing is perfect but myself so you would need to added to that energy budget by what?

The US navy current idea of a super fast rail gun is about the velocity you need for a moon launch not an earth launch.

Oh by the way there is nothing magical about lagrangian points as they are just areas in the gravity fields of two bodies interacting that tend to lock objects into that area at least to the degree that you need far less station keeping fuel to remain yourself on station within them.

There will however still be drift within those areas so you will still need to spend fuel to maintain station location and that go even if you are not having delt V added every time you catch a package from the moon let alone the earth,
.

I may not know a great deal about science, but I can recognise gibberish when I see it. FM is someone whose opinion I respect on most matters scientific. You're an egotist who refuses to admit ever being wrong and you have a pathological insistence on having the last word.

I suspect my opinion is not the minority one.

I don't see any reason to assume that he does know much about science. The entire point of aligning a space elevator cable with a Lagrange point is to take advantage of the overlapping gravitational fields to reduce strain on the cable. Near the earth, the cable "wants" to fall. Beyond a certain point, the cable "wants" to shoot off into space due to the angular momentum. Aligning with a Lagrange point will reduce both effects. With the terminus in space in geosynchronous orbit, there should be no need to use chemical rockets for station keeping. Bill is, himself, the example of the dictum that a little knowledge is a dangerous thing. He has never thought through the exercise, so he dismisses it, and anyone who disagrees with him.

Lord the lagrange points are hundreds of thousands of miles from the surface of earth or must must more then that and a damn space elevator is from the surface of the earth at the equator to Geostationary orbit at 24,000 miles.

Oh, the L points are not fixed in relationship to any point on the turning surface of the earth.

L points and space elevators have nothing to do with each other and you can not align them in any way or in any manner.

Would someone else that understand the concepts please please try to get that point over to them in a way that they can understand!!!!!!

Incidentally, in his science book 'Greetings Carbon-Based Bipeds', Arthur C. Clarke says on page 235-
"We can forget all about space guns on Earth"

He says the launch rail would have to be at least 400 miles long to allow the rocket to accelerate to 25,000 mph escape velocity at a steady 10G acceleration, but that the idea would be pointless because air friction would burn up the rocket!

But he says it'd be quite possible on the airless moon, the rail would only need to be 19 miles long for the rocket to achieve the moon's escape velocity of 5,200 mph at 10G acceleration.
He says astronauts have already endured 10G for short periods, but to make it more comfortable for them, the moon rail could be doubled in length to 38 miles and accel dropped to only 5G .

Off hand I would think that rail guns on the moon would be primarily used to placed materials in near earth/moon space for building projects not for moving humans off the moon into space where the G forces on the cargo does not matter and the rail can be very short.

As Robert Heinlein pointed out in his novel "The Moon is a Harsh Mistress" you better be nice to whoever would control rail guns on the moon as they have what amount to the power of small nuclear bombs that could target anyplace on earth.

Arthur Clarke was often as wrong as he was prescient. A "mass driver" using a rail gun or an electromag accelerating unit within an evacuated containing channel appears feasible for (as I said before) , lifting MATERIEL into space nd thus cut down the costs significantly.
Mass divers or rail guns are capable of extremely high V^2 an by launching wrt to the earth's rotation, they are cheap to get equipment into space. Noone has said that we would launch the crews using the mass drivers . One thing Clarke said that makes some sense
"If anyone says that something is impossible, he is probably wrong"

I just do not see mass drivers working on the earth with both our deep gravity well and deep atmosphere at least in any economic sense.

Now there are other technology such as ground base lasers providing the energy to "rockets" but once more you run into our atmosphere.

The above is why the moon could be a cheap source of building materials for projects into the moon/earth space.

Only humans and high value materials such as electronic should come off earth assuming once more we do not have a heavy lifting abilities of an Orion type system.

still pushing the nuke rockets eh?